Combined spin-orbit torque and spin-transfer torque switching for magnetoresistive devices and methods therefor

ABSTRACT

Spin-Hall (SH) material is provided near free regions of magnetoresistive devices that include magnetic tunnel junctions. Current flowing through such SH material injects spin current into the free regions such that spin torque is applied to the free regions. The spin torque generated from SH material can be used to switch the free region or to act as an assist to spin-transfer torque generated by current flowing vertically through the magnetic tunnel junction, in order to improve the reliability, endurance, or both of the magnetoresistive device. Further, one or more additional regions or manufacturing steps may improve the switching efficiency and the thermal stability of magnetoresistive devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from U.S. ProvisionalApplication No. 62/703,074, filed on Jul. 25, 2018, which isincorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates to, among other things, magnetoresistivedevices and methods for fabricating and/or using the disclosedmagnetoresistive devices.

INTRODUCTION

In one or more embodiments, the present disclosure relates to amagnetoresistive device having a magnetoresistive stack or structure(for example, part of a magnetoresistive memory device and/ormagnetoresistive sensor/transducer device) and methods of manufacturingand operating the described magnetoresistive devices. In one embodiment,an exemplary magnetoresistive stack (for example, used in a magnetictunnel junction (MTJ) magnetoresistive device) of the present disclosureincludes one or more layers of magnetic or ferromagnetic material.

Briefly, a magnetoresistive stack used in a memory device (e.g., amagnetoresistive random access memory (MRAM)) of the present disclosureincludes at least one non-magnetic layer (for example, at least onedielectric layer or a non-magnetic yet electrically conductive layer)disposed between a “fixed” magnetic region and a “free” magnetic region,each including one or more layers of ferromagnetic materials.Information is stored in the magnetoresistive memory stack by switching,programming, and/or controlling the direction of magnetization vectorsin the magnetic layer(s) of the “free” magnetic region. The direction ofthe magnetization vectors of the “free” magnetic region may be switchedand/or programmed (for example, through spin orbit torque (SOT) and/orspin transfer torque (STT)) by application of a write signal (e.g., oneor more current pulses) adjacent to, or through, the magnetoresistivememory stack. In contrast, the magnetization vectors in the magneticlayers of a “fixed” magnetic region are magnetically fixed in apredetermined direction during application of the write signal. When themagnetization vectors of the “free” magnetic region adjacent to thenon-magnetic layer are in the same direction as the magnetizationvectors of the “fixed” magnetic region adjacent to the non-magneticlayer, the magnetoresistive memory stack has a first magnetic state.Conversely, when the magnetization vectors of the “free” magnetic regionadjacent to the non-magnetic layer are opposite the direction of themagnetization vectors of the “fixed” magnetic region adjacent to thenon-magnetic layer, the magnetoresistive memory stack has a secondmagnetic state. The magnetoresistive memory stack has differentelectrical resistances in the first and second magnetic states. Forexample, a resistance (e.g., electrical) of the second magnetic statemay be relatively higher than a resistance of the first magnetic state.The magnetic state of the magnetoresistive memory stack is determined orread based on the resistance of the stack in response to a read currentapplied, for example, through the magnetoresistive stack.

As magnetic memory devices (e.g., MRAM) advance towards smaller processnodes to increase density, individual MTJ bit sizes must laterallyshrink to accommodate tighter pitch and space between bits. However, asthe size and/or aspect ratio of the MTJ bit decreases, so does its shapemagnetic anisotropy. With the decrease in shape anisotropy, the energybarrier of the MTJ may decrease. As the energy barrier decreases,however, the data retention and/or thermal stability of the MTJ bit alsomay decrease. Typically, the decrease in energy barrier of the MTJ bitmay be corrected by increasing the perpendicular anisotropy or magneticmoment of the “free” region by altering itscomposition/material/thickness. However, doing so also may raise thecritical current (described in greater detail below) of the MTJ bit. MTJbits with high critical currents undergo a greater amount of periodicdamage and degeneration during write and/or reset operations andnegatively impact MTJ device (i.e. MRAM) endurance.

The present disclosure relates to devices and methods for writing orotherwise switching the magnetic state of a magnetoresistive memorydevice via STT and/or SOT switching schemes. More particularly, thedescription that follows describes embodiments of MTJ geometries whichintegrate SOT and/or STT switching mechanics, individually or incombination, to provide improved switching efficiency, enabling theswitching of a high energy barrier MTJ bit without the use ofunnecessary high magnitudes of write current. The scope of the currentdisclosure, however, is defined by the attached claims, and not by anycharacteristics of the resulting devices or methods.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure may be implemented in connectionwith aspects illustrated in the attached drawings. These drawings showdifferent aspects of the present disclosure and, where appropriate,reference numerals illustrating like structures, components, materials,and/or elements in different figures are labeled similarly. It isunderstood that various combinations of the structures, components,and/or elements, other than those specifically shown, are contemplatedand are within the scope of the present disclosure.

For simplicity and clarity of illustration, the figures depict thegeneral structure and/or manner of construction of the variousembodiments described herein. For ease of illustration, the figuresdepict the different layers/regions of the illustrated magnetoresistivestacks as having a uniform thickness and well-defined boundaries withstraight edges. However, a person skilled in the art would recognizethat, in reality, the different layers typically have a non-uniformthickness. And, at the interface between adjacent layers, the materialsof these layers may alloy together, or migrate into one or the othermaterial, making their boundaries ill-defined. Descriptions and detailsof well-known features (e.g., interconnects, etc.) and techniques may beomitted to avoid obscuring other features. Elements in the figures arenot necessarily drawn to scale. The dimensions of some features may beexaggerated relative to other features to improve understanding of theexemplary embodiments. The drawings are simplifications provided to helpillustrate the relative positioning of various regions/layers anddescribe various processing steps. One skilled in the art wouldappreciate that the regions are not necessarily drawn to scale andshould not be viewed as representing proportional relationships betweendifferent regions/layers. Moreover, while certain regions/layers andfeatures are illustrated with straight 90-degree edges, in actuality orpractice such regions/layers may be more “rounded”, curved, and/orgradually sloping.

Further, one skilled in the art would understand that, although multiplelayers with distinct interfaces are illustrated in the figures, in somecases, over time and/or exposure to high temperatures, materials of someof the layers may migrate into or interact with materials of otherlayers to present a more diffuse interface between these layers. Itshould be noted that, even if it is not specifically mentioned, aspectsdescribed with reference to one embodiment may also be applicable to,and may be used with, other embodiments.

Moreover, there are many embodiments described and illustrated herein.The present disclosure is neither limited to any single aspect norembodiment thereof, nor to any combinations and/or permutations of suchaspects and/or embodiments. Moreover, each aspect of the presentdisclosure, and/or embodiments thereof, may be employed alone or incombination with one or more of the other aspects of the presentdisclosure and/or embodiments thereof. For the sake of brevity, certainpermutations and combinations are not discussed and/or illustratedseparately herein. Notably, an embodiment or implementation describedherein as “exemplary” is not to be construed as preferred oradvantageous, for example, over other embodiments or implementations;rather, it is intended to reflect or indicate that the embodiment(s)is/are “example” embodiment(s). Further, even though the figures andthis written disclosure appear to describe the magnetoresistive stacksof the disclosed magnetoresistive devices in a particular order ofconstruction (e.g., from bottom to top), it is understood that thedepicted magnetoresistive stacks may have a different order (e.g., theopposite order (i.e., from top to bottom)).

FIG. 1 illustrates a schematic diagram of a region of a magnetoresistivestack utilizing SOT and/or STT switching mechanisms, according to one ormore embodiments of the present disclosure;

FIGS. 2A-2B illustrate schematic diagrams of a region of amagnetoresistive stack utilizing SOT and/or STT switching mechanisms,according to one or more embodiments of the present disclosure;

FIG. 3 illustrates a schematic diagram of a region of a magnetoresistivestack utilizing SOT and/or STT switching mechanisms, according to one ormore embodiments of the present disclosure;

FIGS. 4A-4B illustrate schematic diagrams of a region of amagnetoresistive stack utilizing SOT and/or STT switching mechanisms,according to one or more embodiments of the present disclosure;

FIGS. 5A-5C illustrate schematic diagrams of a region of amagnetoresistive stack utilizing SOT and/or STT switching mechanisms,according to one or more embodiments of the present disclosure;

FIG. 6A illustrates a schematic diagram of a region of amagnetoresistive stack utilizing SOT and/or STT switching mechanisms,according to one or more embodiments of the present disclosure;

FIG. 6B illustrates a cross-sectional view depicting a schematic diagramof a region of a magnetoresistive stack utilizing SOT and/or STTswitching mechanisms, according to one or more embodiments of thepresent disclosure;

FIG. 7A illustrates a magnetoresistive stack during one stage ofmanufacture, according to one or more embodiments of the presentdisclosure;

FIG. 7B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 7A;

FIG. 8A illustrates a magnetoresistive stack during one stage ofmanufacture, according to one or more embodiments of the presentdisclosure;

FIG. 8B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 8A;

FIG. 9A illustrates a magnetoresistive stack during one stage ofmanufacture, according to one or more embodiments of the presentdisclosure;

FIG. 9B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 9A;

FIG. 10A illustrates a magnetoresistive stack during one stage ofmanufacture, according to one or more embodiments of the presentdisclosure;

FIG. 10B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 10A;

FIG. 11A illustrates a magnetoresistive stack during one stage ofmanufacture, according to one or more embodiments of the presentdisclosure;

FIG. 11B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 11A;

FIG. 12A illustrates a magnetoresistive stack during one stage ofmanufacture, according to one or more embodiments of the presentdisclosure;

FIG. 12B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 12A;

FIG. 13A illustrates a top-down view depicting a magnetoresistive stackduring one stage of manufacture, according to one or more embodiments ofthe present disclosure;

FIG. 13B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 13A;

FIG. 14A illustrates a top-down view depicting a magnetoresistive stackduring one stage of manufacture, according to one or more embodiments ofthe present disclosure;

FIG. 14B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 14A;

FIG. 15A illustrates a top-down view depicting a magnetoresistive stackduring one stage of manufacture, according to one or more embodiments ofthe present disclosure;

FIG. 15B illustrates a cross-sectional view depicting themagnetoresistive stack shown in FIG. 15A;

FIG. 16 is a flow chart illustrating an exemplary process formanufacturing a magnetoresistive stack utilizing SOT and/or STTswitching mechanisms;

FIG. 17 is a schematic diagram of an exemplary magnetoresistive memorystack electrically connected to a select device, e.g., an accesstransistor, in a magnetoresistive memory cell configuration;

FIGS. 18A-18B are schematic block diagrams of integrated circuitsincluding a discrete memory device and an embedded memory device, eachincluding an MRAM (which, in one embodiments is representative of one ormore arrays of MRAM having a plurality of magnetoresistive memory stacksaccording to aspects of certain embodiments of the present disclosure).

Again, there are many embodiments described and illustrated herein. Thepresent disclosure is neither limited to any single aspect norembodiment thereof, nor to any combinations and/or permutations of suchaspects and/or embodiments. Each of the aspects of the presentdisclosure, and/or embodiments thereof, may be employed alone or incombination with one or more of the other aspects of the presentdisclosure and/or embodiments thereof. For the sake of brevity, many ofthose combinations and permutations are not discussed separately herein.

DETAILED DESCRIPTION

It should be noted that all numeric values disclosed herein (includingall disclosed thickness values, limits, and ranges) may have a variationof ±10% (unless a different variation is specified) from the disclosednumeric value. For example, a layer disclosed as being “t” units thickcan vary in thickness from (t−0.1t) to (t+0.1t) units. Further, allrelative terms such as “about,” “substantially,” “approximately,” etc.are used to indicate a possible variation of ±10% (unless notedotherwise or another variation is specified). Moreover, in the claims,values, limits, and/or ranges of the thickness and atomic compositionof, for example, the described layers/regions, mean the value, limit,and/or range ±10%.

It should be noted that the description set forth herein is merelyillustrative in nature and is not intended to limit the embodiments ofthe subject matter, or the application and uses of such embodiments. Anyimplementation described herein as exemplary is not to be construed aspreferred or advantageous over other implementations. Rather, the term“exemplary” is used in the sense of example or “illustrative,” ratherthan “ideal.” The terms “comprise,” “include,” “have,” “with,” and anyvariations thereof are used synonymously to denote or describe anon-exclusive inclusion. As such, a device or a method that uses suchterms does not include only those elements or steps, but may includeother elements and steps not expressly listed or inherent to such deviceand method. Further, the terms “first,” “second,” and the like, hereindo not denote any order, quantity, or importance, but rather are used todistinguish one element from another. Similarly, terms of relativeorientation, such as “top,” “bottom,” etc. are used with reference tothe orientation of the structure illustrated in the figures beingdescribed. Moreover, the terms “a” and “an” herein do not denote alimitation of quantity, but rather denote the presence of at least oneof the referenced item.

It should further be noted that, although exemplary embodiments aredescribed in the context of MTJ stacks/structures, the presentinventions may also be implemented in connection with giantmagnetoresistive (GMR) stacks/structures where a conductor (e.g., alayer of copper) is disposed between two ferromagneticregions/layers/materials. Embodiments of the present disclosure may beemployed in connection with other types of magnetoresistivestacks/structures where such stacks/structures include a “fixed”magnetic region. For the sake of brevity, the discussions andillustrations presented in this disclosure will not be repeatedspecifically in the context of GMR or other magnetoresistivestacks/structures (e.g., anisotropic magnetoresistive (AMR) devices),but the discussion and drawings described below are to be interpreted asbeing entirely applicable to GMR and other magnetoresistivestacks/structures (e.g., AMR-type devices).

In this disclosure, the term “region” may be used generally to refer toone or more layers. That is, a region (as used herein) may include asingle layer (deposit, film, coating, etc.) of material or multiplelayers of materials stacked one on top of another (i.e., a multi-layerstructure). Further, although in the description below, the differentregions and/or layers in the disclosed magnetoresistive devices may bereferred to by specific names (e.g., bottom electrode, top electrode,positive Spin Hall (SH) material (i.e., with positive spin hall angle),negative SH material (i.e., with negative spin hall angle which isopposite to the spin hall angle of a “positive” SH material), “fixed”magnetic region, “free” magnetic region), this is only for ease ofdescription and not intended as a functional description or relativelocation/orientation of the layer. Moreover, although the descriptionbelow and the figures appear to depict a certain orientation of thelayers relative to each other, those of ordinary skill in the art willunderstand that such descriptions and depictions are only exemplary. Forexample, though a “free” region of a magnetoresistive stack may bedepicted as being “above” an intermediate layer of that stack, in someaspects the entire depicted magnetoresistive stack may be flipped suchthat the “free” region is “below” the intermediate layer.

In one exemplary embodiment, a magnetoresistive stack of amagnetoresistive device of the present disclosure may be implemented asa STT and/or SOT MRAM element. In such embodiments, the magnetoresistivestack may include an intermediate layer disposed (e.g., sandwiched)between two ferromagnetic regions to form an MTJ device or an MTJ-typedevice. Of the two ferromagnetic regions disposed on either side of theintermediate layer, one ferromagnetic region may be a “fixed” (orpinned) magnetic region, and the other ferromagnetic region may be a“free” magnetic region. The term “free” is intended to refer toferromagnetic regions having a magnetic moment that may shift or movesignificantly in response to applied magnetic fields or spin-polarizedcurrents used to switch the magnetic moment vector. Relatedly, the words“fixed” or “pinned” are used to refer to ferromagnetic regions having amagnetic moment vector that does not move substantially in response tosuch applied magnetic fields or spin-polarized currents. As is known inthe art, an electrical resistance of the described magnetoresistivestack may change based on whether the magnetization direction (e.g., thedirection of the magnetic moment) of the “free” region adjacent to thenon-magnetic layer (e.g., a tunnel barrier) is in parallel alignment orin an antiparallel alignment with the magnetization direction (e.g., thedirection of the magnetic moment) of the “fixed” region adjacent to thenon-magnetic layer. Typically, if the two regions have the samemagnetization alignment, the resulting relatively low resistance isconsidered as a digital “0,” while if the alignment is antiparallel theresulting relatively higher resistance is considered to be a digital“1.” A memory device (e.g., an MRAM) may include multiplemagnetoresistive stacks, which may be referred to as memory cells orelements, arranged in an array of columns and rows. By measuring thecurrent through each cell, the resistance of each cell, and thus thedata stored in the memory array can be read.

In a magnetoresistive device utilizing SOT switching mechanics,switching the magnetization of the “free” region of a magnetoresistivestack may be accomplished by driving a current pulse through a spin-Hall(SH) material proximate (e.g., in contact with or near) the “free”region. The polarity of the current pulse and the polarity of the SHmaterial determines the direction in which the magnetic moment of “free”region is transposed. SH material may have a positive spin hall angle ora negative spin hall angle. SH materials with positive spin hall anglemay be referred to herein as positive SH materials, while SH materialswith negative spin hall angle may be referred to herein as negative SHmaterials. The terms “positive” and “negative” as used in this contextare relative terms only, where positive indicates the material causes,e.g. a clockwise spin current relative to the direction of the currentpulse passing through the SH material, and negative indicates thematerial causes, e.g., a counter-clockwise spin current relative to thedirection of the current pulse through the SH material. Examples of SHmaterials include, but are not limited to, platinum (Pt), beta-tungsten(β-W), tantalum (Ta), palladium (Pd), hafnium (Hf), gold (Au), alloysincluding gold (e.g., AuPt, AuCu, AuW), alloys including bismuth (Bi)and selenium (Se) (e.g., Bi₂Se₃ or (BiSe)₂Te₃), alloys including copper(Cu) and one or more of platinum (Pt), bismuth (Bi), iridium (Ir), orlead (Pb) (e.g., CuPt alloys, CuBi alloys, CuIr alloys, CuPb alloys),alloys including silver (Ag) and bismuth (Bi) (e.g., AgBi alloys),alloys including manganese (Mn) and one or more of platinum (Pt),iridium (Ir), palladium (Pd), or iron (Fe) (e.g., PtMn alloys, IrMnalloys, PdMn alloys, FeMn alloys), or combinations thereof. In one ormore embodiments, platinum (Pt), palladium (Pd), gold (Au), alloysincluding bismuth (Bi) and selenium (Se), CuIr alloys, and CuPt alloysmay act as a positive SH material, while beta-tungsten (β-W), tantalum(Ta), hafnium (Hf), CuBi alloys, CuPb alloys, and alloys includingsilver (Ag) and bismuth (Bi) alloys may act as a negative SH material.In some embodiments, an SH material may act as either a positive SHmaterial or a negative SH material depending on the mode and manner ofdeposition.

The mean current required to be passed through a “free” region in orderto change its magnetic state may be referred to as the critical current(Ic). The critical current is indicative of the current required to“write” data in a magnetoresistive memory cell. Reducing the criticalcurrent is desirable so that, among other things, a smaller accesstransistor can be used for each memory cell and that a higher density,lower cost memory can be produced. A reduced critical current may alsolead to greater longevity and/or durability of a magnetoresistive memorycell.

Embodiments described herein may utilize what may be referred to as spincurrent to switch or aid in switching the magnetic state of the “free”region in an MTJ or MTJ-like device. Current through an SH materialadjacent to (and/or in contact with) the “free” region results in a spintorque acting on the “free” region due to the injection of a spincurrent into the “free” region from the spin-dependent scattering ofelectrons in the SH material. The spin current is injected into the“free” region in a direction perpendicular to the boundary (orinterface) where the “free” region and the SH material meet, andorthogonal to the direction of the current flow. The spin torque appliedto the “free” region by the spin current impacts the magnetic state ofthe “free” region in a manner similar to spin-polarized tunnelingcurrent that flows through the MTJ in traditional STT magnetic tunneljunctions. As the function of STT magnetic tunnel junctions is wellknown in the art, it will not be further described here.

As with write currents in conventional STT MTJ devices, in devices usingSOT switching mechanisms, the direction of torque applied by the spincurrent is dependent on the direction of the current flow in the SHmaterial. In other words, the direction of current flow within the SHmaterial proximate to the “free” region determines the direction oftorque that is applied to the “free” region. Accordingly, the “free”region may be able to be switched between two stable states based ontorque applied by current flowing in the proximate SH material in onedirection or the other. In some embodiments, the “free” region may beable to be switched between two stable magnetic states based on thetorque applied by a STT current flowing in either direction through theMTJ. The magnetic state of the “free” region may also be switching bythe torque resulting from both an STT current by applying an electricalcurrent through MTJ bit and the spin torque by a spin current injectedfrom one or more SH materials by applying an electrical current throughone or more SH materials.

In some embodiments, the torque applied by the spin current (i.e., SOTcurrent) alone is used to switch the “free” region into a particularmagnetic state, whereas in other embodiments, the spin current works asan “assist” to reduce the magnitude of an STT write current required toswitch the magnetic state of the “free” region, where the STT writecurrent travels through the entirety of the MTJ stack to produce a spinpolarized tunneling current between the “free” region and “fixed”region. Reading of data stored by the MTJ stack is accomplished as in aconventional STT MTJ device. For example, a read current, having amagnitude less than that of the critical current of the MTJ stack, isapplied to the MTJ stack to sense the resistance of the MTJ stack. As aperson of ordinary skill in the art would recognize, there are manytechniques that may be used to detect or sense the resistance of the MTJstack. In some embodiments, the resistance sensed based on the readcurrent can be compared with a reference resistance to determine thestate of the “free” region. In some embodiments, a self-referenced readoperation is performed where the resistance through the MTJ is sensed,then the MTJ is written (or reset) so that the “free” region is in aknown state, then the resistance is sensed again and compared with theresistance originally sense. The original state of the “free” region canthen be determined based on whether the resistance sense has changedbased on the write or reset operation. In still other embodiments, amid-point reference read operation may be performed.

For the sake of brevity, conventional techniques related tosemiconductor processing may not be described in detail herein. Theexemplary embodiments may be fabricated using known lithographicprocesses. The fabrication of integrated circuits, microelectronicdevices, microelectric mechanical devices, microfluidic devices, andphotonic devices involves the creation of several layers or regions(e.g., comprising one or more layers) of materials that interact in somefashion. One or more of these regions may be patterned so variousregions of the layer have different electrical or other characteristics,which may be interconnected within the region or to other regions tocreate electrical components and circuits. These regions may be createdby selectively introducing or removing various materials. The patternsthat define such regions are often created by lithographic processes.For example, a layer of photoresist is applied onto a layer overlying awafer substrate. A photo mask (containing clear and opaque areas) isused to selectively expose the photoresist by a form of radiation, suchas ultraviolet light, electrons, or x-rays. Either the photoresistexposed to the radiation, or not exposed to the radiation, is removed bythe application of the developer. An etch may then be employed/appliedwhereby the layer (or material) not protected by the remaining resist ispatterned. Alternatively, an additive process can be used in which astructure is built up using the photoresist as a template.

As noted above, in one aspect, the described embodiments relate to,among other things, methods of manufacturing a magnetoresistive stackhaving one or more electrically conductive electrodes, vias, orconductors on either side of a magnetic material stack. As described infurther detail below, the magnetic material stack may include manydifferent regions of material, where some of these regions includemagnetic materials, whereas others do not. In one embodiment, themethods of manufacturing include sequentially depositing, growing,sputtering, evaporating, and/or providing (which may be referred tocollectively herein as “depositing”) regions which after furtherprocessing (e.g., etching) form a magnetoresistive stack.

In some embodiments, the disclosed magnetoresistive stacks may be formedbetween a top electrode/via/line and a bottom electrode/via/line andwhich permit access to the stack by allowing for connectivity (e.g.,electrical) to circuitry and other elements of the magnetoresistivedevice. Between the electrodes/vias/lines are multiple regions,including at least one “fixed” magnetic region (which may be referred tohereinafter as a “fixed” region) and at least one “free” magnetic region(which may be referred to hereinafter as a “free” region) with one ormore intermediate layers (e.g., a dielectric layer) that forms a tunnelbarrier between the “fixed” region and the “free” region. Each of the“fixed” region and the “free” region may include, among other things, aplurality of ferromagnetic layers. In some embodiments, the “fixed”region (e.g., “fixed” region 20 discussed below) may include a syntheticantiferromagnet (SAF). In some embodiments, a top electrode (and/or)bottom electrode may be eliminated and a bit line may be formed on topof the stack. Additionally, each magnetoresistive stack may be disposedproximate to an SH material. The SH material may be configured to carrycurrent and imparts spin current on the “free” region during write andreset operations. In one or more embodiments, one or more electrodes ofa magnetoresistive stack may include an SH material. In otherembodiments, a magnetoresistive stack may be formed between a topelectrode and a bottom electrode and proximate to an SH material, the SHmaterial being independently connected to a current source. In suchembodiments, the magnetoresistive stack or device may be referred to asa three-terminal magnetoresistive device.

Referring now to FIGS. 1-6B, various switching geometries (e.g., therelative location and orientation of the “free” region and one or moreSH materials) are shown. The simplified illustrations in FIGS. 1-6B donot show all regions and layers of an exemplary magnetoresistive stack,but instead are intended to illustrate the relative location andpositioning of several exemplary switching geometries and the directionof spin current generated by one or more SH materials. Further, althoughthe regions depicted in FIGS. 1-6B are rectangular in shape, this is forsimplicity and clarity only. The magnetoresistive stacks describedherein may have a rectangular, trapezoidal, pyramidal, cylindrical, orother shape.

In some embodiments, the magnetoresistive stacks of the presentdisclosure, specifically the “free” regions of the magnetoresistivestacks may utilize a high aspect ratio (e.g., have a height greater thanor equal to a width or a diameter) or may be otherwise bar-shaped. Oneor more “free” regions as described herein may include cobalt (Co),nickel (Ni), iron (Fe), boron (B), or other ferromagnetic materials.

Referring now to FIG. 1, a magnetoresistive device may include anintermediate layer 115 disposed above and in contact with a “fixed”region 120. A “free” region 110 may be provided above and in contactwith the intermediate layer 115, opposite the “fixed” region 120. Insome embodiments, an SH material 130 (e.g., a positive SH material or anegative SH material) may be disposed adjacent to and in contact withthe “free” region 110. That is, the SH material may be in contact withonly the “free” region 110, and not with the intermediate layer 115 orthe “fixed” region 120. In some embodiments, the SH material 130 mayextend along a width of the “free” region 110. In other embodiments, theSH material 130 may extend only partially along a width of the “free”region 110. In some embodiments, the SH material 130 may contact a topedge of the “free” region 110 and/or a bottom edge of the “free” region110. The SH material 130 may have a height less than or equal to theheight of “free” region 110. As alluded to above, the SH material 130may not touch the intermediate layer 115. Contact of the SH material 130to the intermediate layer 115 may result in a shorting of the MTJ, whichinhibits the ability of the magnetoresistive stack to store data. Insome embodiments, when electrons flow downward through the stack, SHmaterial 130 may impart a spin current to “free” region 110 in adirection perpendicular to the interface of the SH material 130 and“free” region 110, and orthogonal to the direction of electron flow, asshown in FIG. 1. In one or more embodiments, the SH material 130 mayradially cover 20°-120° of “free” region 110 in a plane perpendicular tothe interface of the SH material 130 and “free” region 110.

Referring to FIG. 2A, a magnetoresistive device may include anintermediate layer 115 disposed above and in contact with a “fixed”region 120. A “free” region 110 may be above and in contact with theintermediate layer 115, opposite the “fixed” region 120. In someembodiments, a barrier 140 may be disposed between the “free” region 110and the SH material 130. The barrier 140 may be in contact with both the“free” region 110 and the SH material 130. In some embodiments, the SHmaterial 130 does not contact the “free” region 110. As describedpreviously, SH material 130 may extend along a width of the “free”region 110 or the SH material 130 may extend only partially along awidth of the “free” region 110. The barrier 140 may have a width greaterthan or equal to SH material 130. In some embodiments, barrier 140 mayhave a height greater than or equal to SH material 130. Barrier 140 mayextend from the top edge of “free” region 110. In some embodiments,barrier 140 does not extend past the bottom edge of “free” region 110.In other embodiments, barrier 140 may extend from the top edge of “free”region 110 to the bottom edge of “fixed” region 120, as shown in FIG.2B. In still other embodiments, barrier 140 may extend from a positionadjacent to (and in contact with) “free” region 110 to a positionadjacent to (and in contact with) “fixed” region 120. In one or moreembodiments, barrier 140 (and indirectly SH material 130) may radiallycover 20°-120° “free” region 110 in a plane perpendicular to theinterface of barrier 140 and “free” region 110. As alluded to above,barrier 140 may isolate SH material 130 from “free” region. In someembodiments, when electrons flow downward through the stack, SH material130 may impart a spin current to “free” region 110 in a directionperpendicular to the interface of the barrier 140 and “free” region 110,and orthogonal to the direction of electron flow, as shown in FIGS.2A-2B.

Referring to FIG. 3, a magnetoresistive device may include anintermediate layer 115 disposed above and in contact with a “fixed”region 120. A “free” region 110 may be above and in contact with theintermediate layer 115, opposite the “fixed” region 120. In someembodiments, a positive SH material 130 is placed adjacent to and incontact with “free” region 110. A negative SH material 135 may be placedadjacent to and in contact with “free” region 110, opposite of positiveSH material 130. As described previously, the terms “positive” and“negative” as related to SH materials are relative terms only. It shouldbe understood that a positive SH material 130 may be replaced with anegative SH material 135 and a negative SH material 135 may be replacedby a positive SH material 130 without departing from the scope of thepresent disclosure. The positive SH material 130 and negative SHmaterial 135 may be configured such that a current traveling throughthem in the same direction (e.g., from the top electrode to the bottomelectrode or from the bottom electrode to the top electrode) will applytorque on the magnetic moment of the “free” region 110 in the samedirection. In some embodiments, each of the positive SH material 130 andthe negative SH material 135 may extend along a width of the “free”region 110. In other embodiments, the positive SH material 130 and/orthe negative SH material 135 may extend only partially along a width ofthe “free” region 110.

In some embodiments, the positive SH material 130 and/or negative SHmaterial 135 may contact a top edge of the “free” region 110 and/or abottom edge of the “free” region 110. The positive SH material 130and/or the negative SH material 135 may have a height less than or equalto the height of “free” region 110. In some embodiments, the positive SHmaterial 130 and negative SH material 135 have about the same dimensionsand/or may be on opposing sides of “free” region 110. In otherembodiments, the positive SH material 130 may have a dimension greaterthan or equal to the corresponding dimension of the negative SH material135. In still other embodiments, the negative SH material 135 may have adimension greater than or equal to the corresponding dimension of thepositive SH material 130. In one or more embodiments, positive SHmaterial 130 may radially cover 20°-180° of “free” region 110 in a planeperpendicular to the interface of the positive SH material 130 and“free” region 110. Additionally, or in the alternative, negative SHmaterial 135 may independently radially cover 20°-180° of “free” region110 in a plane perpendicular to the interface of the negative SHmaterial 135 and “free” region 110. In some embodiments, when electronsflow downward through the stack, positive SH material 130 may impart aspin current to “free” region 110 in a direction perpendicular to theinterface of the positive SH material 130 and “free” region 110, andorthogonal to the direction of electron flow. Similarly, when electronsflow downward through the stack, negative SH material 135 may impart aspin current to “free” region 110 in a direction perpendicular to theinterface of negative SH material 135 and “free” region 110, andorthogonal to the direction of electron flow, as shown in FIG. 3.

Referring to FIG. 4A, a magnetoresistive device may include anintermediate layer 115 disposed above and in contact with a “fixed”region 120. A “free” region 110 may be above and in contact with theintermediate layer 115, opposite the “fixed” region 120. In someembodiments, one or more barriers 140 may be disposed between the “free”region 110 and the SH materials 130, 135. A barrier 140 may beassociated with only one SH material 130 or 135 and not with the otherSH material. In some embodiments, such as the ones shown in FIGS. 4A-4B,a magnetoresistive stack includes two barriers 140, one disposed betweenpositive SH material 130 and “free” region 110 and another disposedbetween negative SH material 135 and “free” region 110. Each barrier 140may be in contact with both the “free” region 110 and an SH material130, 135. In some embodiments, neither SH material 130, 135 contacts the“free” region 110. As described previously, SH materials 130, 135 mayextend along a width of the “free” region 110 or the SH materials 130,135 may extend only partially along a width of the “free” region 110.The one or more barriers 140 may have a width greater than or equal to awidth of the SH material 130, 135 with which they are in contact. Insome embodiments, barrier 140 may have a height greater than or equal toa height of the SH material 130,135 with which they contact. Barrier 140may extend from the top edge of “free” region 110. In some embodiments,barrier 140 does not extend past the bottom edge of “free” region 110.In other embodiments, barrier 140 may extend from the top edge of “free”region 110 to the bottom edge of “fixed” region 120, as shown in FIG.4B. In still other embodiments, barrier 140 may extend from a positionadjacent to (and in contact with) “free” region 110 to a positionadjacent to (and in contact with) “fixed” region 120. In one or moreembodiments, barrier 140 (and indirectly the SH material 130) mayradially cover 35°-270° of “free” region 110 in a plane perpendicular tothe interface of barrier 140 and “free” region 110. In some embodiments,when electrons flow downward through the stack, positive SH material 130may impart a spin current to “free” region 110 in a directionperpendicular to the interface of barrier 140 and “free” region 110, andorthogonal to the direction of electron flow. Similarly, when electronsflow downward through the stack, negative SH material 135 may impart aspin current to “free” region 110 in a direction perpendicular to theinterface of barrier 140 and “free” region 110, and orthogonal to thedirection of electron flow, as shown in FIGS. 4A-4B.

Referring to FIG. 5A, a magnetoresistive device may include anintermediate layer 115 disposed above and in contact with a “fixed”region 120. A “free” region 110 may be above and in contact with theintermediate layer 115, opposite the “fixed” region 120. In someembodiments, a barrier 140 may be disposed between the “free” region 110and the SH material 130. The barrier 140 may be in contact with both the“free” region 110 and the SH material 130. In some embodiments, the SHmaterial 130 does not contact the “free” region 110. As describedpreviously, SH material 130 may extend along a width of the “free”region 110 or the SH material 130 may extend only partially along awidth of the “free” region 110. The barrier 140 may have a width greaterthan or equal to a width of the SH material 130. In some embodiments,barrier 140 may have a height greater than or equal to a height of theSH material 130. In one or more embodiments, SH material 130 may have anon-uniform thickness. For example, as depicted in FIG. 5A, portions ofSH material 130 may extend laterally outwards away from “free” region110. In another embodiment, as shown in FIG. 5B, portions of the SHmaterial 130 may extend past an edge of barrier 140 and further extendat approximately a 90° angle laterally outwards away from “free” region110. In such embodiments, SH material 130 may have two or moredimensions greater than one or more of barrier 140 or “free” region 110.In one or more embodiments, portions of SH material 130 may have athickness sufficient to impart a spin current to “free” region 110 withenough magnitude to change the magnetic state of “free” region 110. Insome embodiments, the bit line may be connected to one or more portionsof the SH material 130 extending laterally away from “free” region 110,forming a three-terminal device (e.g., a first terminal connected to theSH material, a second terminal connected to the top electrode, and athird terminal connected to the bottom electrode).

With renewed reference to FIG. 5A, barrier 140 may extend from the topedge of “free” region 110. In some embodiments, barrier 140 does notextend past the bottom edge of “free” region 110. In other embodiments,as shown in FIG. 5B, barrier 140 may extend past the bottom edge of theSH material 130. In still other embodiments, barrier 140 may extend fromthe top edge of “free” region 110 to the bottom edge of “fixed” region120, as shown in FIG. 5C. In still other embodiments, barrier 140 mayextend from a position adjacent to (and in contact with) “free” region110 to a position adjacent to (and in contact with) “fixed” region 120.In one or more embodiments, barrier 140 (and indirectly SH material 130)may radially cover approximately 35°-320° of “free” region 110 in aplane perpendicular to the interface of the barrier 140 and “free”region 110, allowing electrons to circulate around a majority of acircumference of the “free” region 110. In some embodiments, whenelectrons flow along SH material 130, a spin current may be imparted to“free” region 110 in a direction perpendicular to the flow of electrons,as shown in FIGS. 5A-5C. In some embodiments, this flow of electronsimparts enough torque to switch the magnetic moment of the “free” region110 between two stable magnetic states.

Referring now to FIGS. 6A-6B, a magnetoresistive device may include anintermediate layer 115 disposed on and in contact with a “free” region110. The magnetoresistive device may further include a “fixed” region120 above and in contact with the intermediate layer 115. The “free”region 110, intermediate layer 115, and “fixed” region 120 may have thesame or similar widths and/or flush edges, as shown in FIGS. 6A-6B. Themagnetoresistive device shown in FIG. 6A may extend further “into thepage” or “out of the page” with one or more additional layers formed“behind” or “in front” of the shown region. FIG. 6B represents an axialcross-section of the region shown in FIG. 6A. One or more barriers 140may be positioned along the edge of “free” region 110, intermediatelayer 115, and “fixed” region 120. The one or more barriers 140 mayextend along a length of the “free” region 110, intermediate layer 115,and “fixed” region 120. As shown in FIGS. 6A-6B, the magnetoresistivedevice may include an in-plane MTJ. In one or more embodiments, amagnetoresistive stack includes two barriers 140 positioned on opposingsides of “free” region 110, intermediate layer 115, and “fixed” region120. In one or more embodiments, the magnetoresistive stack may furtherinclude a barrier layer 140 disposed to the side of the “free” region110 and in contact with both SH material 130 and “free” region 110 atthe vertical interfaces. In one or more embodiments, themagnetoresistive stack may further include a barrier layer 140 disposedto the side of and below (or top) the “free” region 110 and in contactwith both SH material 130 and/or “free” region 110 at the vertical andhorizontal interfaces. The SH material 130 may extend across a width of“free” region 110 and/or along a length of “free” region 110. In someembodiments, SH material 130 may have a height greater than or equal tothe height of barrier 140. SH material 130 may extend upwards past thetop surface of “free” region 110 or may even extend past the top surfaceof “fixed” region 120. In some embodiments, the portions of the SHmaterial 130 that extend upward past the top surface of “fixed” region120 may be connected directly to the bit line, forming a three-terminaldevice. In some embodiments, the SH material 130 does not touch theintermediate layer 115 and/or the “fixed” region 120. In someembodiments, when electrons flow along SH material 130, a spin currentmay be imparted to “free” region 110 in a direction perpendicular to theinterface of “free” region 110 and SH material 130, and orthogonal tothe direction of electron flow, as shown in FIG. 6. In one or moreembodiments, SH material 130 and “free” region 110 may be configuredsuch that SH material 130 imparts a spin current to “free” region 110 ofenough magnitude to switch “free” region 110 between stable magneticstates.

An exemplary method of manufacturing a magnetoresistive stack with SOTswitching (e.g., a magnetoresistive stack including one of thegeometries discussed above) will now be discussed with reference toFIGS. 7A-15B. It should be understood that although the exemplary methodis discussed in the context of one specific switching geometry, thetechniques, methods, and principles described herein are applicable toany of the described switching geometry embodiments. Further, aspects orfeatures of one or more exemplary methods may be combined with aspectsor features of any other described exemplary method. Additionally, aspreviously stated, commonly performed conventional techniques related tosemiconductor processing may not be specifically described herein.Rather, the description herein is intended to highlight aspects ofexample methods of manufacturing a magnetoresistive stack utilizing STTand/or SOT switching.

FIG. 7A shows a magnetoresistive stack including an MTJ according to oneor more embodiments of the present disclosure after, e.g., an etchingprocess or lithographic microfabrication processing step. FIG. 7B showsa cross section of the magnetoresistive stack of FIG. 7A. Referring toFIGS. 7A-B, a magnetoresistive stack may include a bottom electrode 210,which may be integrated into or otherwise formed on a substrate 205(e.g., a silica substrate). A “fixed” region 120 may be positioned aboveand in contact with the bottom electrode 210, and an intermediate layer115 may be above and in contact with the “fixed” region 120. A “free”region 110 may be positioned above and in contact with intermediatelayer 115 and a top electrode 220 may be above and in contact with“free” region 110. One or more oxides (e.g., silica) may be applied tothe stack by, e.g., physical vapor deposition (PVD), other thin filmfabrication processes, and/or other technique known in the art.

FIG. 8A shows a magnetoresistive stack that has been coated with oxide(i.e., an oxide-coated magnetoresistive stack), according to one or moreembodiments. FIG. 8B shows a cross section of the magnetoresistive stackof FIG. 8A. Referring to FIGS. 8A-8B, in one or more embodiments, anoxide layer 215 is formed over the substrate 205 and/or the topelectrode 220. In some embodiments, the oxide-coated magnetoresistivestack may include one or more oxide regions 215 disposed above and incontact with substrate 205. Oxide region 215 may cover the entire topsurface of substrate 205. In other embodiments, only part of the topsurface of substrate 205 is covered by oxide region 215. Theoxide-coated magnetoresistive stack may further include an oxide region215 disposed above and in contact with top electrode 220. In one or moreembodiments, oxide may be applied such that an oxide region 215completely covers the thickness of intermediate layer 115. In someembodiments, oxide region 215 may contact substrate 205, bottomelectrode 120, intermediate layer 115, and/or free region 110. Infurther embodiments, oxide region 215 may be conformal around themagnetoresistive stack and cover the vertical side walls of one or moreregions of the magnetoresistive stack. In one or more embodiments, abarrier material (e.g., MgO, metal oxide, SiN, metalloid conductor) maybe deposited on an oxide-coated magnetoresistive stack by chemical vapordeposition (CVD), PVD, or other method known in the art.

FIG. 9A shows a magnetoresistive stack that has been coated with barriermaterial (i.e., a barrier-coated magnetoresistive stack), according toone or more embodiments. FIG. 9B shows a cross section of thebarrier-coated magnetoresistive stack of FIG. 9A. Referring to FIGS.9A-9B, in one or more embodiments, a barrier-coated magnetoresistivestack may include a barrier 140 disposed above and in contact with oxideregion 215. Barrier 140 may contact oxide region 215, top electrode 220,and/or “free” region 110. In some embodiments, barrier 140 does notcontact intermediate region 115. Barrier 140 may cover the entire heightof “free” region 110. In one or more embodiments, an SH material 130(e.g., platinum (Pt), beta-tungsten (β-W), and/or tantalum (Ta)) may bedeposited on the barrier-coated magnetoresistive stack.

FIG. 10A shows a magnetoresistive stack that has been coated with SHmaterial (i.e., an SH material-coated magnetoresistive stack), accordingto one or more embodiments. FIG. 10B shows a cross section of themagnetoresistive stack of FIG. 10A. Referring to FIGS. 10A-10B, an SHmaterial-coated magnetoresistive stack may include SH material 130disposed above and in contact with barrier 140. In some embodiments, theSH material 130 does not contact any layers/regions of themagnetoresistive stack other than barrier 140.

In one or more embodiments, an auxiliary oxide may be deposited on theSH material-coated magnetoresistive stack by PVD, other thin filmfabrication method, or other method known in the art. FIG. 11A shows amagnetoresistive stack that has been coated with an auxiliary oxide(i.e., an auxiliary oxide-coated magnetoresistive stack), according toone or more embodiments. FIG. 11B shows a cross section of the auxiliaryoxide-coated magnetoresistive stack of FIG. 11A. Referring to FIGS.11A-11B, one or more auxiliary oxides 235 may be disposed above and incontact with SH material 130. In some embodiments auxiliary oxide 235may also contact barrier 140.

In some embodiments, the auxiliary oxide-coated magnetoresistive stackmay be etched, abraded, and/or otherwise polished (e.g., viachemical-mechanical planarization (CMP)). CMP is a process of eveningsurfaces through a combination of chemical and physical means. In someembodiments, the auxiliary-oxide coated magnetoresistive stack may bepolished via any previously-described means to expose a surface of topelectrode 220 flush with a top surface of auxiliary oxide 235, as shownin FIG. 12A (cross-section in FIG. 12B). A surface of barrier 140 mayalso be exposed that is flush with the top surface of auxiliary oxide235. In some embodiments, after the magnetoresistive stack undergoes CMPto expose a surface of top electrode 220, the remaining auxiliary oxide235 may be etched (e.g., angled etch or oblique etch) or otherwiseablated from the magnetoresistive stack.

FIG. 13A shows a top-down view of an array of magnetoresistive stacksincluding MTJs after the auxiliary oxide has been removed, according toone or more embodiments. FIG. 13B shows a cross-section of onemagnetoresistive stack of the array shown in FIG. 13A along line13B-13B. As shown in FIGS. 13A-13B, the SH material 130 and barrier 140radially cover 360° of “free” region 110 in a plane perpendicular to theinterface of barrier 140 and “free” region 110. Further etching steps(angled etches, rotational etches, oblique etches) may be taken tocreate the switching geometries described within the present disclosure.For example, a first etching step may etch (e.g., angled etch or obliqueetch) certain regions of the SH material 130 and expose regions of thebarrier 140 above oxide region 215, as shown in FIGS. 14A-14B. In someembodiments, a second etching step (e.g., angled etch or oblique etch)may be taken to expose a surface of “free” region 110 byremoving/ablating SH material 130 and barrier 140 from a portion of“free” region 110, as shown in FIGS. 15A-15B. Each magnetoresistivestack in the array of magnetoresistive stacks shown in FIG. 15A have theswitching geometry shown in FIG. 5A. Similarly, any of the switchinggeometries described herein may be manufactured using the methodsdescribed above. After the SH material 130 and barrier 140 are etched toa desired geometry, further layers and/or connections may be made aboveand/or in contact with top electrode 220.

FIG. 16 is a flow chart of a method 300 of manufacturing amagnetoresistive stack utilizing STT and/or SOT switching, according toone or more embodiments of the present disclosure. The method 300 mayinclude depositing an oxide on a magnetoresistive stack that includes anMTJ to form an oxide-coated magnetoresistive stack (step 310). Themethod 300 may further include depositing barrier material on theoxide-coated magnetoresistive stack to form a barrier-coatedmagnetoresistive stack (step 320). In some embodiments, the method 300may include depositing SH material on the barrier-coatedmagnetoresistive stack (step 330). The method 300 may further includedepositing an auxiliary oxide on the SH material-coated magnetoresistivestack (step 340). In some embodiments, the method 300 may includeperforming CMP on the auxiliary oxide-coated magnetoresistive stack(step 350). In one or more embodiments, performing CMP on the auxiliaryoxide-coated magnetoresistive stack may expose a top electrode and/orbarrier of the magnetoresistive stack. The method 300 may furtherinclude at least partially etching the auxiliary oxide layer (step 360).In some embodiments, all of the auxiliary oxide is etched or otherwiseremoved from the magnetoresistive stack. In one or more embodiments,method 300 may include at least partially etching SH material (step370). In some embodiments, the method 300 may further include at leastpartially etching the barrier. The SH material and barrier may be etchedin any pattern to form any of the exemplary switching geometriesdescribed herein.

As alluded to above, the magnetoresistive devices of the presentdisclosure, including one or more switching geometries described herein,may be implemented in a sensor architecture or a memory architecture(among other architectures). For example, in a memory configuration, themagnetoresistive devices may be electrically connected to an accesstransistor and configured to couple or connect to various conductors,which may carry one or more control signals, as shown in FIG. 17. Themagnetoresistive devices of the current disclosure may be used in anysuitable application, including, e.g., in a memory configuration. Insuch instances, the magnetoresistive devices may be formed as anintegrated circuit comprising a discrete memory device (e.g., as shownin FIG. 18A) or an embedded memory device having a logic therein (e.g.,as shown in FIG. 18B), each including MRAM, which, in one embodiment isrepresentative of one or more arrays of MRAM having a plurality ofmagnetoresistive stacks, according to certain aspects of certainembodiments disclosed herein.

Although various embodiments of the present disclosure have beenillustrated and described in detail, it will be readily apparent tothose skilled in the art that various modifications may be made withoutdeparting from the present disclosure.

What is claimed is:
 1. A magnetoresistive device comprising: a fixedregion having a fixed magnetic state; a free region configured to have afirst magnetic state and a second magnetic state, wherein the devicestores a first value when the free region is in the first magnetic stateand the device stores a second value when the free region is in thesecond magnetic state; a dielectric layer between the free region andthe fixed region; and a spin-Hall (SH) material proximate to at least aportion of the free region, wherein current through the SH materialgenerates spin current in a direction perpendicular to a plane betweenthe SH material and the free region; wherein the device is configuredsuch that current may be passed through the SH material without passingthrough the free region.
 2. The device of claim 1, wherein a currentflowing in a first direction through the SH material switches the freeregion to the first magnetic state, and wherein a current flowing in asecond direction switches the free region to the second magnetic state.3. The device of claim 1, wherein the SH material is also proximate toat least a portion of the fixed region.
 4. The device of claim 1,wherein the fixed region comprises a synthetic antiferromagnet.
 5. Thedevice of claim 1, wherein the SH material comprises at least one ofplatinum, beta-tungsten, tantalum, palladium, hafnium, gold, an alloyincluding gold, an alloy including bismuth and selenium, an alloysincluding copper, an alloy including manganese, iridium, selenium, orone or more combinations thereof.
 6. The device of claim 1, wherein theSH material radially covers at least about 180° of the free region, in aplane perpendicular to an interface of the SH material and the freeregion.
 7. The device of claim 6, wherein the SH material covering afirst radial portion of the free region has a thickness greater than theSH material covering a second radial portion of the free region.
 8. Thedevice of claim 1, further comprising a barrier disposed between the SHmaterial and the free region.
 9. The device of claim 8, wherein thebarrier has a height greater than or equal to a height of the SHmaterial and/or the barrier has a width greater than or equal to a widthof the SH material.
 10. A magnetoresistive device comprising: a fixedregion having a fixed magnetic state; a free region configured to have afirst magnetic state and a second magnetic state, wherein the devicestores a first value when the free region is in the first magnetic stateand the device stores a second value when the free region is in thesecond magnetic state; a dielectric layer between the free region andthe fixed region; a first spin-Hall (SH) material proximate to at leasta portion of the free region, wherein current through the first SHmaterial generates a first spin current in a direction perpendicular toa plane between the SH material and the free region; a second SHmaterial proximate to at least a portion of the free region, whereincurrent through the second SH material generates a second spin currenthaving a polarity opposite a polarity of the first spin current.
 11. Thedevice of claim 10, wherein the first SH material and the second SHmaterial are also proximate to at least a portion of the fixed region.12. The device of claim 10, further comprising a first barrier, disposedbetween the first SH material and the free region, and a second barrier,disposed between the second SH material and the free region.
 13. Thedevice of claim 10, wherein the first SH material forms an interfacewith the free region and covers about 30° to about 180° of the freeregion, in a plane perpendicular to an interface of the first SHmaterial and the free region; and the second SH material forms aninterface with the free region and covers about 30° to about 180° of thefree region, in a plane perpendicular to an interface of the second SHmaterial and the free region.
 14. The device of claim 10, wherein thefirst SH material is disposed opposite the second SH material, relativeto the free region.
 15. The device of claim 10, wherein the first SHmaterial comprises at least one of platinum, palladium, gold, an alloyincluding bismuth and selenium, CuIr alloy, CuPt alloy, or one or morecombinations thereof; and the second SH material comprises at least oneof beta-tungsten, tantalum, hafnium, CuBi alloy, CuPb alloy, an alloyincluding silver and bismuth, or one or more combinations thereof.
 16. Amagnetoresistive device comprising: a fixed region having a fixedmagnetic state; a free region; a dielectric layer between the freeregion and the fixed region; and a spin-Hall (SH) material that radiallycovers at least about 180° of the free region, in a plane perpendicularto an interface of the SH material and the free region, wherein the SHmaterial covering a first radial portion of the free region has athickness greater than the SH material covering a second radial portionof the free region.
 17. The device of claim 16, wherein the free regionis configured to have a first magnetic state and a second magneticstate, and wherein the device stores a first value when the free regionis in the first magnetic state and the device stores a second value whenthe free region is in the second magnetic state.
 18. The device of claim16, further comprising a barrier disposed between the SH material andthe free region.
 19. The device of claim 16, wherein the device isconfigured such that current may be passed through the SH materialwithout passing through the free region.
 20. The device of claim 16,wherein the fixed region comprises a synthetic antiferromagnet.